Hey @yeahvip,
When you have a question, please open a new topic. And reference other topics instead of commenting on them. For when you write in an old topic. It can trigger emails to the people involved. And not everyone likes to receive emails from old subjects.
About your question.
XID mapping only exists for entities. Consequently, edges that belong to this entity must contain the blank node in order to be mapped.
Blank nodes(unique identifiers) are used in that case. A Tour of Dgraph
In general Dgraph does not use XID, only UIDs. Internally Dgraph handles this, but it is not open for users manipulation.
If you have URI, URL, UUID, GUID, BIC, UDID, SSID, NPI, shortuuid, Snowflake, MongoID and etc. You must use this approach here Get started with Dgraph.
Cheers.